This invention relates to a marine vessel transmission with (a) an input drive shaft extending along an input drive shaft axis designed to connect to a marine engine, (b) an output drive shaft designed to apply a torque to a propeller having a gear reduction for the input drive shaft, (c) a housing which at least partially surrounds the input drive shaft and the output drive shaft, and (d) a secondary output drive shaft which protrudes from the housing in a torque introduction journal and is arranged on a secondary output drive shaft gearwheel, which is arranged in the torque path located behind the input drive shaft.
Prior marine vessel transmissions are known, such as DE 1 945 797 or the DE 10 2008 018 703 A1. Marine vessel transmissions are designed to be connected to a main engine of a marine vessel from which they receive a torque, which is transferred by the transmission to the propeller of the marine vessel in an altered form. In order to supply electrical units of the marine vessel with power, it is known, on one part of the transmission to channel a portion of the engine output torque to an electric generator that supplies power for the on-board electrical network.
The disadvantage of known marine vessel transmissions is that there is a relatively high amount of wear at the coupling point between the generator and the torque induction journal.
FR 894 621 A discloses a steam turbine in which a rotor of a generator is permanently connected with a turbine shaft and the junction between rotor and turbine shaft acts as storage for the rotor on one side.
U.S. Pat. No. 3,635,048 discloses a gear coupling which surrounds the two gear wheels and where the oil from one housing side of the gear coupling is directed through the area between the gear wheels to the other housing side of the gear coupling.
The aim of the invention is to reduce the wear at the coupling point between the generator and the torque induction journal. The invention solves the problem by means of a marine vessel transmission in accordance with claim 1.
The invention has an advantage in that the rotor is mechanically defined and is not borne in a mechanically overly-constrained way as is the case with solutions provided from the prior art. In this way the present rotor can feature a bearing, for example a rolling bearing, which touches one side of the rotor. On the opposite side the rotor is borne onto a torque introduction journal, without which a further bearing would be required on this end.
Another advantage is that installation space for a further bearing is saved, since the rotor is directly borne onto the torque induction journal, which reduces the necessary installation space.
A further advantage of the solution created by this invention is the reduced wear. Since the generator does not project as far out because of the direct bearing on the torque induction journal, the generator is less susceptible to vibrations. During operation, marine vessel transmissions vibrate constantly, as they generally share a foundation with a marine diesel. This vibration is transferred onto the generator, whose free end vibrates relatively to the housing of the marine vessel transmission. This vibration spreads to the junction between the secondary output drive shaft and the rotor which can result in the wearing down of the areas of contact between the two. The less the electric generator protrudes from the housing, the smaller the amplitude of this vibration at the junction and thus the less significant the wear.
Within the framework of the description at hand, the term marine vessel transmission is in particular understood to mean a transmission with which a crash-stop maneuver can be carried out multiple times, whereby the term crash-stop maneuver is understood to mean a maneuver in which the negative value of the nominal torque can be applied whilst driving ahead at full speed with the nominal torque.
The electric generator is preferably attached to the housing in such a way that it can be detached. For example, the generator possesses a generator housing with which it is interlocked with, or as the case may be screwed onto, the housing of the marine vessel transmission. This enables the generator to be exchanged quickly. Furthermore, it is possible to run the marine vessel transmission without the generator and to add the generator at a later date.
The electric generator is preferably connected with the secondary output drive shaft by means of an interlocking connection, e.g. splined shaft, feather key, splined couplings or toothed shaft. Such a connection is particularly robust and resilient against vibrations.
It is preferable that the electric generator is designed in such a way that it can also be run as an electric motor, especially if the generator is designed so that it can be run as an asynchronous (induction) motor.
In one application, the secondary output drive gearwheel is stepped up with regards to the input drive shaft. If the secondary output drive gearwheel is stepped up with regards to the input drive shaft, it means that it rotates more quickly than the input device shaft. In this case, the use of a generator in the form of an asynchronous generator is particularly convenient. Synchronous generators have a smaller installation space at the same power rating, so it would initially be expected that the use of a synchronous generator or synchronous engine is more convenient. However, the same amount of power can be harnessed with an asynchronous generator in the same or smaller installation space as with a synchronous generator. An added advantage is that a synchronous generator creates higher voltages at high speeds than an asynchronous generator. However, highly variable voltages require a lot of energy during the processing of the electrical power, meaning that the combination of a step-up transmission and the use of an induction generator is particularly advantageous.
It is especially favourable if the input drive shaft is coupled with the torque induction journal with a gear transmission ratio of at least 1 to 1.5, whereby the gear transmission ratio is preferably smaller than 1 to 3. In other words, for every rotation of the input drive shaft, the torque pin does at least 1.5, or a maximum of 3 rotations.
A transmission ratio between 2 and 2.4 is particularly favourable. The generator can be used effectively as a motor with these given gear transmission ratios. Electric generators or engines have a particularly small installation space at the same power rating, the higher their speed of rotation. The larger the gear transmission ratio, the more favourable it is for the use of the generator as an auxiliary drive. The smaller the gear transmission ratio, the more convenient it is for the use of the generator for the production of electrical energy. The indicated transmission ratio range has proven itself to be the optimal compromise.
In accordance with a preferred embodiment of the invention, the marine vessel transmission is a reversible transmission. This means that all step-ups or reductions in both directions of rotation can be carried out immediately. This is especially advantageous if a marine vessel has two permanent propellers, as in a preferred embodiment. These permanent propellers must constantly rotate against each other, whereby the marine diesel constantly only rotates in one direction. In this way it is possible to drive both propellers with two structurally identical marine vessel transmissions.
In accordance with a preferred embodiment, the rotor is connected with the secondary output drive shaft at a junction and the secondary output drive shaft has an oil duct through which the oil can be conducted into the junction. For example, the oil duct is created through a central longitudinal bore through the secondary output drive shaft. It is then possible to direct oil though this oil duct from inside the housing to a free end of the torque induction journal protruding from the housing, so that the oil escaping there lubricates the junction between the rotor and the secondary output drive shaft.
It is particularly favourable if the rotor surrounds the secondary output drive shaft at the pin-end in such a way that the oil coming from the oil duct of the secondary output drive shaft can be directed away from the pin end. In other words, once the oil has left the oil duct, it flows in the direction of the housing, where it goes back into the housing through an oil opening. In this way, it is possible to use the oil which is already present in the marine vessel transmission to lubricate the joint.
The generator preferably has a housing and a shaft seal by means of which oil escaping the oil duct is prevented from leaking into the housing. This ensures that the electrical components of the generator cannot be damaged by oil.
It is preferable that the marine vessel transmission has (a) an input drive shaft gearwheel arranged on the input drive shaft, (b) a first pinion shaft which runs coaxially to the input shaft drive and upon which a first pinion is arranged, and (c) a second pinion shaft which runs parallel to the input drive shaft and upon which a pinion shaft gearwheel, which meshes with the input drive shaft, and a second pinion are arranged, whereby (d) a spur gear is arranged on the input drive shaft, which meshes with the first pinion and the second pinion. In a preferable embodiment, the secondary output drive gearwheel meshes with a secondary input drive gearwheel, whereby the secondary output drive gearwheel is arranged on the first pinion or the second pinion. This results in a particularly simply structured marine vessel transmission.
A switchable input drive shaft clutch may be arranged on the input drive shaft, by means of which the input drive shaft gearwheel can be connected with the first pinion shaft so that they rotate together. It is also useful if this input drive shaft clutch is a hydraulically switchable multiple disk clutch.
It is possible that, for example, the input drive shaft gearwheel and/or the pinion shaft gearwheel are designed as a tooth system of an external housing of the input drive shaft clutch.
Preferably, a hydraulically switchable pinion shaft clutch is arranged on the second pinion shaft, by means of which the pinion shaft gearwheel can be connected with the second pinion shaft so that they rotate together.
When activating the input drive shaft clutch and the pinion shaft clutch, it is favourable if an electric control unit is provided, which is designed in such a way that the input drive shaft clutch and the pinion shaft clutch can be switched, so that a maximum of one of the two constantly establishes a rotating connection.
In one embodiment, the marine vessel transmission has (i) an intermediate shaft on which a spur gear and a bevel pinion are arranged, (ii) an input drive shaft gearwheel arranged on the input drive shaft, (iii) a first pinion shaft which extends coaxially to the input drive shaft and on which a first pinion is arranged, and (iv) a second pinion shaft which runs parallel to the input drive shaft and on which a pinion shaft gearwheel, which meshes with the input drive shaft gearwheel, and a second pinion shaft are arranged, whereby the first pinion and the second pinion mesh with the spur gear, and a spur bevel gear is arranged on the output drive shaft which, together with the bevel pinion, forms a bevel drive unit. This type of marine vessel transmission is particularly well suited to a Z-motor which is used, for example, in yachts. Preferably, the output drive shaft extends along an output drive shaft axis which runs at an angle of 75° to the input drive shaft axis.
It is favourable if the generator has a power rating of between 50 and 150 kilowatts. A power rating of the marine vessel transmission can thus be between, for example, 8 and 12 times larger than the power rating of the generator.
The invention also encompasses a marine propulsion with a diesel engine, a marine vessel transmission according to the invention, whose input drive shaft is connected to the diesel engine, and a permanent propeller, which is drivable by means of the output drive shaft or is at least indirectly coupled with the output drive shaft. It is favourable if this marine propulsion has a converter to change a frequency into a current indicated by the generator. This converter can also work particularly well as a rectifier, so that a battery pack can be recharged as an energy storage device. It is favourable if the marine vessel transmission is connected with the marine propulsion without having to use the clutch, meaning that a smaller installation space is required.
Preferably, the marine propulsion possesses an electric energy storage device in the form of at least a rechargeable battery, which is connected with the converter in such a way that it can be recharged by the generator. The rectifier can then act as an inverter so that the generator is supplied with electrical power of a specified voltage and frequency in such a way that a predefined torque is applied to an output drive shaft. The marine vessel transmission is preferably designed in such a way that in the installation position of the marine vessel transmission, the input drive shaft axis runs primarily horizontally.